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. Author manuscript; available in PMC: 2011 Apr 1.
Published in final edited form as: Cancer Res. 2010 Oct 5;70(20):8045–8054. doi: 10.1158/0008-5472.CAN-10-2352

Figure 4.

Figure 4

PARP inhibition of hypoxic tumor cells in vivo induces DNA damage. (A) Schematic of ABT-888 treatment. RKO xenografts were treated twice daily for 5 days with 50 mg/kg ABT-888 and then collected for immunohistochemical (IHC) staining and determination of PARP activity. (B) Relative enzymatic PARP activity of tumor lysates collected 2 h after the final ABT-888 treatment verifies PARP inhibition in vivo. (C) Representative IHC staining of vehicle and ABT-888 treated tumors show decreased RAD51 staining in EF5-avid subregions. ABT-888 treated tumors show increased γH2AX and cleaved caspase-3 (CC3) staining (white arrows) in EF5 positive subregions compared to vehicle treated tumors. Scale bar represents 100 microns. (D) Quantification of γH2AX and CC3 fluorescent intensity within aerobic (EF5 negative) and hypoxic (EF5 positive) tumor subregions. Analysis based on 4-8 fields per tumor for 3-5 tumors per treatment group. *, P<0.05.